Asus p7p55d-e motherboard
I changed from a radeon 5770 to a radeon r92-270 graphics card and a Gigabyte 400w to a Corsair CX500 PSU.
Now the PC will boot but only as far as Windows, after that it immediately shuts down like the power has been cut. So... thinking it might be the graphics card drivers tried safe mode, and then took out the card and put my old one back.
With just the replaced PSU and original graphics card it won't even boot to safemode. I get a few seconds of my old desktop on a normal boot and nothing of safe mode before the power cuts again. I've re-checked all of my connections MANY times at this point.
What have I done wrong?